Troubleshooting LOGO! Soft Comfort V8.2 on macOS Mojave

Problem Overview

LOGO! Soft Comfort V8.2, the programming environment for Siemens LOGO! 8 logic modules, exhibits persistent UI hangs (spinning beach ball) and program freezes on Apple's macOS Mojave (10.14). The application is not officially certified for Mojave; the last macOS releases officially listed in the LSC V8.2 release notes are Mac OS X 10.7 Lion through 10.11 El Capitan. This article documents the verified symptoms, the underlying software architecture that triggers the freeze, and the field-proven workarounds used by automation engineers and panel builders who must continue LSC development on Intel-based Macs after the 2018 Apple OS release cycle.

Affected Software and Environment

LOGO! Soft Comfort V8.2 is the Java-based Integrated Development Environment (IDE) used to program, simulate, and transfer circuit programs to the LOGO! 8 (6ED1052-xxx08-0BAx) and LOGO! 8.3 base modules. The macOS build is distributed as a DMG installer that ships its own bundled Java 8 Runtime Environment (JRE). The compatibility matrix published by Siemens with the V8.2 release notes only lists macOS versions through 10.11 El Capitan.

Environment components relevant to the bug:

• Operating System: macOS 10.14.x (Mojave), all supplemental updates 10.14.0 through 10.14.6.
• Application: LOGO! Soft Comfort V8.2 (build 8.2.0.x), including the JRE-bundled variant and the standalone Java install.
• Java Runtime: Oracle JRE 8 (1.8.0_xxx) or the bundled JRE shipped with the LSC installer. Newer JRE 9/10/11 are not used by LSC V8.2.
• Hardware: Intel-based Mac (MacBook Pro, MacBook Air, iMac, Mac mini, Mac Pro) and Apple Silicon under Rosetta 2 (no native ARM build exists).

According to the official LOGO! product documentation, the macOS version compatibility list has not been extended for the V8.2 release. See the Siemens Industry Online Support portal for the latest supported operating system matrix and the LOGO! Soft Comfort product page at siemens.com/logo.

Root Cause Analysis

Three intersecting root causes produce the Mojave symptoms.

1. Java Cocoa Implementation Drift

LSC V8.2 ships against the Java 8 Cocoa implementation, which Apple deprecated in macOS 10.14 in favor of the Metal-backed rendering pipeline. The Cocoa event-pump threads that LSC uses to redraw the circuit diagram and update I/O status icons interact badly with the new AppKit threading model, producing UI-thread stalls that the OS renders as the spinning beach ball (the OS Watchdog timer fires after 2 seconds of unresponsiveness).

2. Mojave Power-Nap and Process Throttling

macOS Mojave introduced more aggressive background throttling for helper processes. LSC's auto-save and circuit-simulation helper threads lose scheduling slices; the main AWT event dispatch thread blocks while waiting for the simulation result, triggering the same OS-level UI stall.

3. New Privacy/Disk-Access TCC Prompts

Mojave's Transparency, Consent, and Control (TCC) subsystem forces every application to request explicit permission to access the file system, Documents folder, and removable media. LSC's auto-save dialog and the LSC project file (*.lsc, *.lld) open/save dialogs require this consent. Without an explicit grant, the OS silently blocks the I/O; LSC waits indefinitely, producing the same visible symptom as a delay-block hang.

Symptoms Catalog

The Mojave failure modes reported by engineers fall into four categories. Each must be confirmed before applying the matching workaround.

Step-by-Step Recovery Procedure

Apply the following steps in order. Each is a prerequisite for the next.

Step 1 — Verify the macOS Point Release

Click the Apple menu → About This Mac. If the build is 10.14.0, apply the 10.14.1 supplemental update immediately. The macOS Mojave 10.14.1 update shipped in late October 2018 and resolved a number of Cocoa AWT stalls on third-party Java applications. For builds 10.14.4 and later, the spinning ball returns for some users when the LOGO! 8 LOGOComfort simulation panel is foregrounded for more than 60 seconds. The root cause is in the Metal-backed windowing path; the workarounds in Steps 3-5 are still required.

Step 2 — Grant Required TCC Permissions

1. Open System Preferences → Security & Privacy → Privacy.
2. Select Full Disk Access from the left column.
3. Click the padlock, authenticate, and add the LOGOComfort.app bundle located in /Applications/Siemens/LOGOComfort_V82/.
4. Repeat for Files and Folders and Automation if present.
5. Quit LSC completely (Cmd+Q) and relaunch.

Step 3 — Repair the Disk and Recover from a Corrupt Cache

Persistent spinning ball behavior is frequently caused by a damaged file-system catalog on the boot volume after the Mojave in-place upgrade. Apple documents a recovery procedure using the macOS Recovery partition.

1. Shut down the Mac.
2. Power on and immediately hold Command (⌘) + R until the Apple logo or spinning globe appears.
3. Select Disk Utility from the macOS Utilities window.
4. Choose the boot volume (typically Macintosh HD) from the sidebar.
5. Click First Aid → Run. Wait for "Operation successful".
6. Quit Disk Utility, choose Restart from the Apple menu, then launch LSC V8.2.

This procedure corresponds to Apple's published macOS Recovery user guide. The full Mojave release notes are available from Apple's macOS Mojave product page.

Step 4 — Reset the LSC User Profile

Stale or corrupted LSC user preferences in ~/Library/Preferences/com.siemens.LOGOComfort.plist can lock the Java VM into a partial init state. Remove and let the application regenerate:

rm -f ~/Library/Preferences/com.siemens.LOGOComfort.plist
rm -rf ~/Library/Application\ Support/Siemens/LOGOComfort/
rm -rf ~/Library/Caches/Siemens/LOGOComfort/

Re-launch LSC; the first start re-creates the cache and a fresh user profile.

Step 5 — Run LSC Inside a Windows Virtual Machine (Verified Workaround)

For installations where LSC behavior remains unstable on Mojave, the most reliable workaround is to run the Windows build of LSC V8.2 inside a virtual machine on the same Mac. This eliminates the Java Cocoa dependency entirely and provides full access to the LOGO! 8 Ethernet/IP communication drivers.

Configure the VM with at least 4 GB RAM and 2 virtual CPUs. Enable bridged networking so the LSC program transfer (FTP over Ethernet) can reach the LOGO! 8 base module at its default IP 192.168.0.10 (or the address assigned in the LOGO! 8 Setup menu).

Step 6 — Alternative macOS Host Path

Engineers who must remain on a native macOS build can boot into an external macOS 10.13 High Sierra or 10.11 El Capitan partition, then run LSC V8.2 there. The High Sierra partition is the last macOS release where LOGOComfort was reliably functional without the spinning ball. Use Carbon Copy Cloner or Apple's built-in Disk Utility Restore to create the bootable external volume.

Java Runtime Tuning

LSC V8.2 uses the Java 8 JRE shipped with the installer, but engineers sometimes install a system-wide JRE to support other IDEs. The following JVM flags reduce the AWT thread stalls on Mojave when added to /Applications/Siemens/LOGOComfort_V82/LOGOComfort.app/Contents/Info.plist under the Java dictionary:

<key>Properties</key>
<dict>
  <key>apple.awt.UIElement</key>
  <string>false</string>
</dict>
<key>Arguments</key>
<array>
  <string>-Xmx2048m</string>
  <string>-Dawt.useSystemAAFontSettings=on</string>
  <string>-Dsun.java2d.opengl=true</string>
</array>

These flags force the Java 2D pipeline to OpenGL, bypassing the broken Metal-backed path. Save the file, then re-sign the application:

codesign --force --deep --sign - /Applications/Siemens/LOGOComfort_V82/LOGOComfort.app

Verification Procedure

After applying the workarounds, perform the following functional tests to confirm the fix:

1. Launch LSC V8.2 and create a new circuit diagram.
2. Insert an On-Delay (B001), Off-Delay (B002), and On/Off-Delay (B003) function block from the Special Functions library.
3. Open the block's parameter dialog and change the time constant. The dialog must close within 1 second and the change must appear in the property pane.
4. Press F2 to start the simulation. The simulation clock must advance in real time without dropping below 60 % of real time on a 2017 MacBook Pro or newer.
5. Connect to a live LOGO! 8 base module via Ethernet and transfer the program (PC → LOGO!). The Ethernet transfer window must reach 100 % within 30 seconds for a typical 200-block program.
6. Quit and relaunch. The application must start within 8 seconds and display the start page without the spinning ball.

If the spinning ball still appears on a fresh user profile with Full Disk Access granted, the VM-based path is the only remaining option until Siemens releases an updated LSC build with Mojave/Catalina support.

Preventive Measures

To minimize future regression risk on macOS point releases:

• Do not upgrade macOS on a Mac used for LSC development past the last certified version (10.11) without first taking a Time Machine backup.
• Maintain a dedicated Windows VM with snapshot capability and revert to a known-good snapshot before each LSC upgrade.
• Subscribe to the Siemens Industry Online Support notification list for LOGO! product updates; watch for the next LSC V8.3 or V8.4 release that adds Mojave/Catalina support.
• Keep a copy of the offline LOGO! 8 System Manual (6ED1050-1AA00-0BA8) for the function block reference; the delay-block parameters (current value, parameter set, retentivity) are accessed by clicking the block, not by dragging, which avoids the AWT stall.

Troubleshooting Matrix

Frequently Asked Questions